Grid structure



P 1958 w. J. BONGERS 2,851,628

GRID STRUCTURE Original Filed June 13, 1951 FIGA V V -FIG.3 \J

IN VEN TOR WILHELHUS JJJJJ s BONGER$ AGENT "or during the heating of the frame.

United rates atent GRID STRUCTURE Wilhelmus Johannes Bongersliiudhoven, Netherlands, assignor, by mesne assignments, to North American Philips Company, lnc., New York, N.'Y., a corporation of Delaware Original application June 13, 1951, Serial No. 231,404, now Patent No. 2,726,686, dated December 13, 1955. giglilgg and this application June 30, 1955, Serial No.

2 Claims. (Cl. 313-348) This application is a division'of my application Serial 128%. 231,404, filed June 13, 1951, now Patent No. 2,726,- This invention relates to an improved jig for windmg grids on flat frames for use in electric discharge tubes.

Grids are commonly formed in pairs by arranging two frames, each having an aperture, against one another or against a winding jig, and by winding the grid Wire across the frames and apertures of the winding structure. After the wire has been secured to the frames, preferably with the use of solder, for example gold, and after the wire portions protruding beyond the frames have been removed, the frame-shaped grids can be removed from the winding structure. It is very difiicult to wind wire of less than 25 microns in diameter at a uniform pitch of less than 50 microns on a winding structure having flat surfaces because the wire does not have a uniform cross sectional area. The irregularities of such a fine wire cause it to tilt when wound on flat edge surfaces of a winding structure causmg, in turn, irregularities in the pitch of the grid wires. The grid wires as commonly wound barely touch the flat grid sides of the frame, but do rest upon the remaining flat surfaces of the frame.

The main object of the invention is to provide an improillled structure for winding grid wires at a uniform pitc Further objects of the invention will appear as the specification progresses.

According to the invention an improved structure for winding grid wires is composed of one or more frames each having an aperture and a sharp edged jig to contain saiid frames so that the grid wires only rest on said sharp e ges.

Since the diameter of the wire is very small and the tensile force exerted on the wire is very high during the winding operation the sharp side of the edges must be rounded so that the wire is not cut during said operation Accordingly, the term sharp edge is to be understood to mean here an edge with which the apex of the cross-sectional area is smaller than 90. The term grid plane of the winding structure is to be understood to mean each plane of this structure in which a surface of the grid frame provided with Wires is located. Since, with a winding jig having grooved edges according to the invention, the wire only bears on sharp edges, the possibility that exactly an uneven part should engage the sharp edge is much smaller, so that tilting is substantially avoided.

In many cases the winding jig comprises two grid frames, their rear sides engaging one another; their edges must therefore be bevelled towards the rear and form a V-shaped groove across which the grid wire is wound. However, as an alternative, the winding jig may be constituted by a primarily rectangular winding jig having grooved edges across which the wire is wound, while a grid frame is clamped to one side surface of the jig or 2,851,628 Patented Sept. 9, 1958 one frame to each of the side surfaces. Before and after the grid wire has passed by each frame, it is then bent over a sharp edge. In this case use may be made of grid frames of conventional form, i. e. withoutbevelled edges. The winding jig may have recesses to accommodate the grid frames.

In order that the invention may be more clearly understood and readily carried into elfect, it will now be described more fully with reference to the accompanying drawing, in which Fig. 1 is a front view and Fig. 2 a side view of a grid Fig. 3 illustrates how grids are wound and Fig. 4 is a cross sectional viewv ofa thin grid'wire;

Fig. 5 is a side view of partof such-a wire and Figs. 6, 7, 8 and 9 show further embodiments-of a winding jig.

Referring to Fig. l, the frame 1, which is preferably made of molybdenum, supports on one side a plurality of grid wires 2 of, for example, 5/1. of thickness. Theframe for example is, constituted by a disc having a diameter of 9 mms., two segments of which have been cut off, so that straight edges for winding the grid wire are formed. The thickness of the frame is, for example, 0.5 mm. and provision is made, for example, of a rectangular aperture of 4 by 4 ms. When a winding jig built up from two of such frames is formed by arranging the: frames against one another in the usual manner, the grid wire bears through a stretch of twice the thickness of the frames i. e. for 1 mm. in this case, on the flat side edge. Consequently the wire not only bears on the sharp edges, but also on the entire side surface, since the edge is a angle. If part of the wire having. a cross-sectional area as shown by way of example in Fig. 4 finds its way to this side edge, the wire tilts over, so that a divergence in pitch is produced. Such divergences 7 only occur in short stretches of the wire, as is shown in Fig. 5, but it has been found that the possibility of tilting is nevertheless so great that practically no regular grid can be wound, since such a grid frequently has about 80 turns, which corresponds in this case with a wound length of wire of cms. for two grids, whilst the said irregularities frequently succeed one another in intervals of a few decimeters or less. If, as is shown in Figs. 2 and 3, two frames 1 and 4 having bevelled sides 3 and 5 are arranged against one another so that the bevelled sides form a V-shaped groove, the wire bears with its parts 6 only on two sharp edges. The possibility that an irregularity as shown in Fig. 4 should exactly contact with such an edge is much smaller than if the wire is supported in each turn on twice the length of 1 mm. In any event, it is now possible to wind grids with an extremely regular pitch. Subsequent to the winding operation the grid wires are soldered, for example, with the use of gold, to the frames and the wire portions beyond the frames 6 are removed so that two flat grids are obtained, after the frames have been removed from the winding former.

In the embodiment shown in Figs. 6 and 7 two frames 9 and 10 are clamped against the flat sides of the Winding jig 8, after which the wire 2 is wound on the winding former. The jig 8 has grooved edges 11 in accordance with the invention, so that the wire is supported between the grid planes only by two sharp edges. If desired, the frames 10 may be slipped under the grid wires, after having wound the wires on the jig. For this purpose the winding jig has to be provided with recesses, so that the frames can he slipped under the wires without coming into contact herewith. In this case the frames may be shaped in the conventional form. As is shown in Figs. 8 and 9, the winding jig may, as an alternative,

ice

have a cross-sectional area of the shape of a polygon.

It is obvious that the frames may have other shapes and, if desired, be in part secured to one another in the shape of a strip, whilst a winding jig may be provided with a plurality of frames. For this purpose the winding structure may have a triangular, quadrangular or polygonal cross-sectional area.

While the invention has been described with reference to specific examples and applications thereof other modifications will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. As an article of manufacture a grid comprising a washer-like frame having a substantially flat surface portion and having an aperture pierced through said member approximately in the center of said surface, two opposite edges of said surface being defined by flat sides of said member, the line defined by the intersection of one with the line defined by the intersection of said surface and the other of said sides, the included angle between each of said sides and said surface being less than 90; and a plurality of fine wires having a diameter less than 25 microns and having irregularities at spaced intervals, said Wires extending across said flat surface from one of said edges to the other and being spaced apart by less than 50 microns and making contact with said surface only at said edges, said wires being aflixed to said member by being soldered thereto in the region of each of said edges.

2. The article of manufacture of claim 1 in which said edges are rounded slightly.

References Cited in the file of this patent UNITED STATES PATENTS 2,397,233 Bingley Mar. 26, 1946 2,549,551 Walsh Apr. 17, 1951 2,610,387 Borland Sept. 16, 1952 2,704,879 Diggle Mar. 29, 1955 2,772,376 Cook et a1. NOV. 27, 1956 

